Sometimes pitfalls are constructed for the reception of single animals, such as the elephant, the hippopotamus, and the rhinoceros. These are made chiefly in two modes. The pitfalls which are intended for catching the three last mentioned animals are tolerably large, but not very deep, because the size and weight of the prisoners prevent them from making their escape. Moreover, a stout stake, some five feet or more in length, and sharpened at the top, is placed in the middle of the pit, so that the animal falls upon it and is impaled. The pits are neatly covered with sticks, leaves, and earth, so ingeniously disposed that they look exactly like the surface of the ground, and are dangerous, not only to the beasts which they are intended to catch, but to men and horses. So many accidents have happened by means of these pits, that when a traveller goes from one district to another he sends notice of his coming, so that all the pitfalls that lie in his way may be opened. Elephants are, of course, the most valuable game that can be taken in these traps, because their tusks can be sold at a high price, and their flesh supplies a vast quantity of meat. As the elephant is a terrible enemy to their cornfields and storehouses, the natives are in the habit of guarding the approaches by means of these pitfalls, and at first find their stratagem totally successful. But the elephants are so crafty that they soon learn caution from the fate of their comrades, and it is as difficult to catch an elephant in a pitfall as it is to catch an old rat in a trap. Having been accustomed to such succulent repasts, the elephants do not like to give up their feasts altogether, and proceed on their nocturnal expeditions much as usual. But some of the oldest and wariest of the herd go in front, and when they come near the cultivated ground, they beat the earth with their trunks, not venturing a step until they have ascertained that their footing is safe. As soon as they come to a pitfall, the hollow sound warns them of danger. They instantly stop, tear the covering of the pitfall to pieces, and, having thus unmasked it, proceed on their way. The pitfall which is made for the giraffe is constructed on a different principle. Owing to the exceedingly long limbs of the animal, it is dug at least ten feet in depth. But, instead of being a mere pit, a wall or bank of earth is left in the middle, about seven feet in height, and shaped much like the letter A. As soon as the giraffe tumbles into the pit, its fore and hind legs fall on opposite sides of the wall, so that the animal is balanced on its belly, and wastes its strength in plunging about in hopes of finding a foothold.